A Research On Fault Diagnosis And Fault Tolerant Technology Of IGBT In Active Power Filters

With the rapid development of society and science and technology, people demandmore and more on the quality of electricity. Active power filter(APF) is widely used for itcan deal with harmonics of various frequencies dynamically and make compensationsreactively. However, like most other power electronic devices, APF will break down inemergencies or when operated unproperly, which can lead to breakdown of the wholesystem or other disastrous consequences such as explosion. Therefore, in order to improvethe reliability of the system, prolong the safe operation time of APF and decrease the losscaused by the breakdown of APF and failure in the operation of system, it is of importanttheoretical meaning and practical value to research on diagnosing faults and fault-tolerantcontrol of active power filter.When IGBT of active power filter(APF) has run for a long time, it is prone to failurewhich may result in serious consequences. On this basis, an method of diagnosing thebreakdown of IGBT based on the current Clark vector transformation and a fault toleranttopology of APF are proposed in this paper. APF restrains harmonics through outputtingcurrent of the same amplitude and frequency of harmonics and the opposite phase with theload current. With the output current having really complex waveform, this paper worksout the current transformation through extracting the components of fundamentalcomponent of the output current of APF and diagnoses faults in open circuit by makinguse of the trajectory of the current Clark vector and the slope of the trajectory, and amethod of diagnosing fault By DSP software program is put forward. Meanwhile, a faulttolerant topology of active power filter and a specific implement method of fault-tolerantcontrol are provided. Besides, a related simulation model of the control system of activepower filter is constructed in the MATLAB/Simulink simulation platform. The simulationresults verify the validity of this control scheme.This paper makes a detailed design of the simulation model of grid-connect APFcontrolling system, the parameter of main circuit in the system and the simulation of each submodule on MATLAB/Simulink platform. Through a simulation experiment, this paperproves that the effect of this simulation model is good enough for further fault simulation.After that, simulation experimental research is done on the method of diagnosing fault andthe fault tolerant topology brought up in this paper on the simulation experimentalplatform, which verify the validity and reliability of them.